One of Oracle's JVMs is named HotSpot the other, inherited from BEA Systems, is JRockit. Oracle provides tests that verify the proper operation of implementations of the Java Virtual Machine. We intend that this specification should sufficiently document the Java Virtual Machine to make possible compatible clean-room implementations. The specification for the JVM was published as the blue book, whose preface states: As of 2006, changes to the specification to support changes proposed to the class file format (JSR 202) are being done as a maintenance release of JSR 924. Starting with Java Platform, Standard Edition (J2SE) 5.0, changes to the JVM specification have been developed under the Java Community Process as JSR 924. Any Java application can be run only inside some concrete implementation of the abstract specification of the Java virtual machine. The main reason for this omission is to not unnecessarily constrain implementers. The garbage collection algorithm used and any internal optimization of the Java virtual machine instructions (their translation into machine code) are not specified. It is a part of java runtime environment. The Java virtual machine is an abstract (virtual) computer defined by a specification. Eclipse OpenJ9 is another open source JVM for OpenJDK.

The commercially supported Java releases available from Oracle are based on the OpenJDK runtime. The JVM reference implementation is developed by the OpenJDK project as open source code and includes a JIT compiler called HotSpot. Having a specification ensures interoperability of Java programs across different implementations so that program authors using the Java Development Kit (JDK) need not worry about idiosyncrasies of the underlying hardware platform.

The JVM is detailed by a specification that formally describes what is required in a JVM implementation. Overview of a Java virtual machine (JVM) architecture based on The Java Virtual Machine Specification Java SE 7 EditionĪ Java virtual machine ( JVM) is a virtual machine that enables a computer to run Java programs as well as programs written in other languages that are also compiled to Java bytecode.

Java se 16 development kit